Solaris™ Internals: Core Kernel Components

15.2. Page Cache and Virtual Memory System

The virtual memory system is implemented around the page cache, and the file system makes use of this facility to cache files. This means that to understand file system caching behavior, we need to look at how the virtual memory system implements the page cache.

The virtual memory system divides physical memory into chunks known as pages; on UltraSPARC systems, a page is 8 kilobytes. To read data from a file into memory, the virtual memory system reads in one page at a time, or “pages in” a file. The page-in operation is initiated in the virtual memory system, which requests that file's file system to page in a page from storage to memory. Every time we read in data from disk to memory, we cause paging ...